The mechanisms of action of oligomeric proteins that participate in higher levels of organization will be studied to gain added insight towards our understanding of subunit-subunit interactions, self-assembly processes, and the advantages the cell derives from the functional ordering of its proteins. Work will continue on the quaternary structure of the alpha-keto acid dehydrogenase enzyme complexes and on the three-dimensional structures of their component enzymes. Electron microscopic and spectroscopic data on various aggregate forms of the photoreceptor C-phycocyanin will be used in conjunction with its x-ray crystallographic structure to study the self-assembly and function of phycobilisomes. In addition, the high resolution refinement of an invertebrate monomeric hemoglobin and the solutions of a dimeric invertebrate hemoglobin should also be completed during this next period.